Our work this year to increase understanding of the molecular pharmacology of mood stabilizers has focused on three main areas: 1) Human Brain Studies: Comparison of mRNA and protein levels of G- proteins and Protein Kinase C (PKC) isozymes in Bipolar vs. Normal post- mortem human brains revealed the following differences: in occipital cortex, mRNA levels of PKC-alpha and -gamma were decreased, while G- alpha-i2 was increased in Bipolar compared to Normal brains. PKC-alpha and -gamma protein levels were also decreased in Bipolar occipital cortex, as was G-alpha-i1,2. 2) In vivo microdialysis studies: Comparison of the effects of Ethoxyidazoxan v. Idazoxan on levels of norepinephrine (NE) and serotonin (5-HT) in hippocampus and occipital cortex of awake rats revealed no significant qualitative differences, though Ethoxyidazoxan was more potent. 3) Cell culture studies: We found that the anticonvulsant, antimanic drug, sodium valproate, induces morphological changes in glial and neuronal cell cultures which are not observed with 2-ene valproate, a nonteratogenic metabolite which shares valproate's anticonvulsant properties. Similar morphological changes were induced by probenecid, a drug which can inhibit cellular uptake of folic acid. Thus, valproate's teratogenicity may involve inhibition of folate uptake. Assays of 3H-GABA uptake in neural vs. glial cells suggest valproate may differentially affect subtypes of GABA transporters. We have developed a post-mitotic human neural cell culture system which appears to utilize GABA, glutamate, ACh , and glycine, and possesses active Na and Ca channels, and receptors for glutamate, GABA, ACh, and opiates. Experiments are currently underway to explore valproate's effects on Na currents and GABA synthesis using this system. We are also making stable transfections of these cells with various receptors and transporters in order to allow them to be studies in a homogeneous human CNS-like environment.